This invention relates to a process for dimerization of olefins.
It is well known in the art to employ supported alkali metal catalysts for such conversions as propylene dimerization. It is also well known to use alkali metal carbonates as catalyst support. For example, the use of potassium on potassium carbonate for the catalytic dimerization of propylene to 4-methyl-1-pentene has been disclosed in U.S. Pat. No. 4,544,790, U.S. Pat. No. 4,609,637 and U.S. Pat. No. 4,656,154. Typically, in the process of propylene dimerization to 4-methyl-1-pentene, the propylene is passed over a catalyst bed comprising extruded potassium carbonate impregnated with potassium metal. However, when this process is started up or shut down more than twice, it is observed that the catalyst bed is plugged, presumably by polymeric products formed during startups and shutdowns even though on shutdown the temperature is lowered to a range where polymerization would not be expected. The plugged catalyst bed must therefore be replaced, incurring additional cost and time.